Brain-computer interfaces or BCIs: types and uses

Brain-computer interfaces (BCIs) or brain-machine interfaces (BMIs) enable the transformation of brain signals into specific actions and commands within a computer or machine. This is a rapidly evolving field that presents numerous opportunities for controlling devices beyond the physical limitations of the individual.

BCIs are categorised into three types depending on the method employed for recording electrical activity: invasive, partially invasive and non-invasive. The first approach involves implanting electrodes inside the brain or in direct contact with brain tissue, while the second entails placing them on the surface of the brain or in its vicinity. Both systems enable the collection of a substantial amount of accurate data, albeit requiring advanced surgical procedures and posing significant health risks.

However, the most common method used today is electroencephalography or EEG, a non-invasive technique that involves the temporary placement of electrodes on the scalp. These are then connected to a computer capable of converting electrical signals into interpretable brain waves, whose anomalies allow for the detection of conditions such as epilepsy, Alzheimer’s, sleep disorders or brain injuries, among others.

Uses of brain-computer interfaces

One of the fields with the greatest interest in the development of BCIs is medicine. This technology holds significant potential in enhancing quality of life for people with physical and motor disabilities, as it enables the control of any machine solely through brain activity. It also contributes to the treatment of mental health conditions such as depression, anxiety or attention deficit disorder. While aiding in injury rehabilitation, it also assists in the recovery of brain functions such as memory and neuroscience research.

Concurrently, brain-computer interfaces have uses in other areas:

• In education, by understanding brain responses to various types of training, identifying methods that enhance student concentration and creating personalised learning approaches.
• In industry, by allowing workers to control machines more effectively and safely.
• In sport, by monitoring the mental state of athletes and how it differs at various stages of training and competition.
• In art and entertainment, with countless uses in interactive artwork, video games and virtual reality environments, promoting immersive and more inclusive experiences.
• In home automation, by assisting people with disabilities in everyday tasks (such as turning on lights, opening blinds or adjusting room temperature).

Currently, BCIs developed across these fields are divided into four general categories: brain-interface, brain-prosthesis, brain-text-and-image and brain-brain devices.

1. Brain-interface devices

These are systems specifically designed to enable communication between the human mind and a machine or computer.

A good example is Emotiv Epoc, a headset that makes use of electrodes to control various interfaces through the user’s thoughts. This is a simple and intuitive device that can be configured in just five minutes, designed for scalable brain research. Of particular note is its use of saline-based, gel-free sensors, making it suitable for both children and adults, as well as studies on awake or sleeping subjects.

The company also sells other headsets with varying levels of precision and specialisation.

2. Brain-prosthesis devices

These include technology that captures brain signals and links them to specific actions in prostheses or robotic systems, proving to be highly beneficial for people with physical disabilities or motor impairments.

One such device is the LUKE Arm, a prosthetic arm initially developed for the United States Defence Advanced Research Projects Agency (DARPA). It is the most advanced bionic appendage in existence, capable of performing multiple movements simultaneously, while providing each finger with good mobility. It can adjust to the length of the shoulder, elbow or wrist, as well as hold delicate objects, pinch small items and provide a lateral grip for objects such as keys, pencils or cutlery.

3. Brain-text-and-image devices

These brain-computer interfaces capture brain signals and interpret them to generate text or images on a screen. They are primarily used in support and communication applications for people with disabilities that affect their ability to speak or write.

One of the devices belonging to this category is the Unicorn Speller, a software that combines an electrode-based cap with a small screen containing numbers and letters. The user needs to focus on the desired symbol for a few seconds, allowing it to be selected and displayed in a text box. The interface also provides text-reading capabilities and an option for drawing or painting, along with a predictive mode to enhance writing efficiency.

4. Brain-brain devices

Finally, these devices enable the exchange of information, thoughts or emotions between people, whether in a unidirectional or bidirectional manner.

This technology remains in its early stages of development, although we are able to identify one example: the BrainNet social network. The project uses an electrode helmet and the classic Tetris game to enable three users to synchronise their thoughts: two of them act as information transmitters, while the third receives the signals and places the video game blocks in the indicated position.

The success rate of this communication system exceeds 80%, indicating that such brain-computer interfaces are viable and can make significant contributions to science and research.

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